Page 832 - College Physics For AP Courses

820
Chapter 18 | Electric Charge and Electric Field
Problems & Exercises
18.1 Static Electricity and Charge: Conservation of Charge
1. Common static electricity involves charges ranging from nanocoulombs to microcoulombs. (a) How many electrons are needed to form a charge of (b) How many electrons must be removed from a neutral object to leave a net charge of ?
2. If electrons move through a pocket calculator during a full day's operation, how many coulombs of charge
moved through it?
3. To start a car engine, the car battery moves electrons through the starter motor. How many coulombs of
charge were moved?
4. A certain lightning bolt moves 40.0 C of charge. How many
fundamental units of charge is this?
18.2 Conductors and Insulators
5. Suppose a speck of dust in an electrostatic precipitator has protons in it and has a net charge of –5.00
nC (a very large charge for a small speck). How many electrons does it have?
6. An amoeba has protons and a net charge of
0.300 pC. (a) How many fewer electrons are there than protons? (b) If you paired them up, what fraction of the protons would have no electrons?
7. A 50.0 g ball of copper has a net charge of .
What fraction of the copper's electrons has been removed? (Each copper atom has 29 protons, and copper has an atomic mass of 63.5.)
8. What net charge would you place on a 100 g piece of sulfur if you put an extra electron on 1 in of its atoms? (Sulfur has an atomic mass of 32.1.)
9. How many coulombs of positive charge are there in 4.00 kg of plutonium, given its atomic mass is 244 and that each plutonium atom has 94 protons?
18.3 Conductors and Electric Fields in Static Equilibrium
10. Sketch the electric field lines in the vicinity of the conductor in Figure 18.47 given the field was originally uniform and parallel to the object's long axis. Is the resulting field small near the long side of the object?
Figure 18.47
11. Sketch the electric field lines in the vicinity of the conductor in Figure 18.48 given the field was originally uniform and parallel to the object's long axis. Is the resulting field small near the long side of the object?
Figure 18.48
12. Sketch the electric field between the two conducting plates shown in Figure 18.49, given the top plate is positive and an equal amount of negative charge is on the bottom plate. Be certain to indicate the distribution of charge on the plates.
Figure 18.49
13. Sketch the electric field lines in the vicinity of the charged insulator in Figure 18.50 noting its nonuniform charge distribution.
Figure 18.50 A charged insulating rod such as might be used in a classroom demonstration.
14. What is the force on the charge located at in Figure 18.51(a) given that ?
Figure 18.51 (a) Point charges located at 3.00, 8.00, and 11.0 cm along the x-axis. (b) Point charges located at 1.00, 5.00, 8.00, and 14.0 cm along the x-axis.
This OpenStax book is available for free at http://cnx.org/content/col11844/1.14